(1) Field of the Invention
The present invention relates to a trenched power semiconductor structure and a fabrication method thereof, and more particularly relates to a trenched power semiconductor structure with schottky diode and a fabrication method thereof.
(2) Description of the Prior Art
In present, the trend in development for trenched power semiconductor devices turns toward the performance of switching speed. The increasing of switching speed is especially helpful for reducing switching loss in high-frequency applications. Among various solutions for improving switching speed, it is an effective method to add a schottky diode in the power semiconductor structure.
FIG. 1 is a circuit diagram showing a metal-oxide-semiconductor (MOS) transistor T1 with a schottky diode SD1 to improve switching loss. As shown, the MOS transistor T1 has a body diode D1 connected to the schottky diode SD1 in parallel. Because the turn-on voltage of the schottky diode SD1 is smaller than that of the body diode D1, the current would be directed from the source electrode S through the schottky diode SD1 to the drain electrode D when the MOS transistor T1 becomes forwardly biased, and the body diode D1 would not be conducted.
Because of the minority carriers, the switching of the body diode D1 is quite slow, which may cause unwanted time delay to result in additional switching loss. The usage of schottky diode with no minority carrier, is able to improve the problems of time delay and switching loss when the body diode D1 is conducted.